Typically, a dimming LED circuit, such as a LED driver, is used to control the brightness of LEDs. LEDs are increasingly being used instead of incandescent bulbs. LEDs provide several advantages over conventional light sources, which include lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.
Dimming LED circuits have several methods to control the brightness of LEDs. One method is pulse width modulation (PWM) dimming. PWM dimming switches a switch to control the average of LED current supplied to the LEDs. Another method is direct-current (DC) dimming. DC dimming controls the LED current that is supplied to the LEDs. An alternative method is combining PWM and DC dimming.
Dimming LED circuits can, however, present several disadvantages. One disadvantage of a dimming LED circuit is unpredictable operation across multiple LEDs of the same installation. Other disadvantages encountered with a dimming LED circuit are the limited number of parameters that are available and the inconsistency of the parameters. Typically, some of the parameters include photometric response, LED temperature, LED color output over time, gamma variation, and LED intensity variation.
Another disadvantage of conventional dimming LED circuits is that LEDs usually have shortened lifetimes. Typically, the LED input power of the dimming LED circuit is increased as the LED drive respectively increases the brightness of the LEDs to a desired luminance level. This increased LED drive reduces the overall LED source lifetime and thus leads to additional replacements and increased costs.